JPH048613B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine idling speed control device for an industrial vehicle such as a forklift.

[Prior art]

In industrial vehicles, this function prevents engine speed from suddenly decreasing and stalling when a load is accidentally connected without pressing the accelerator pedal while the engine is idling, and also improves engine startability. In order to improve
An engine idling speed control device using a vacuum diaphragm has already been proposed.

For example, in the device shown in Japanese Patent Application Laid-Open No. 56-44430, in order to open and close the valve 3 by operating a throttle lever 5 fixed to the throttle valve 3 in FIG. A vacuum diaphragm 10 with a piston rod 11 engaging the lever 5 is attached. A spring 15 is housed within the vacuum diaphragm 10 and biases the piston rod 11 in a direction to push it out. The other end of the vacuum diaphragm 10 communicates with an intake manifold 14 via a pipe 12 and a connector 13 to introduce negative intake pressure. When the intake negative pressure is small, the piston rod 11 is pushed out by the spring 15 and pushes the throttle lever 5 to open the throttle valve 3. On the other hand, when the negative pressure becomes large, the piston rod 11 resists the pressing force of the spring 15. It is pulled inward, allowing the throttle valve 3 to close under the action of a spring (not shown).

Valve 3 is mostly closed when idling, but if the engine is incorrectly loaded,
As the engine speed decreases, the negative pressure in the intake manifold also decreases, and the spring 15 in the vacuum diaphragm 10 pushes the piston rod until it balances the suction force due to the negative pressure according to the load, and the throttle lever 5 Press to open valve 3 to prevent engine stall.

However, such a conventional idling speed control device includes a vacuum diaphragm 10 for operating the throttle valve 3, a pipe 12 for introducing negative pressure into the vacuum diaphragm 10, a connector 13 for connecting the pipe 12 to the intake manifold 14, etc. The number of parts required is large, which increases manufacturing costs, and when a rubber-based negative pressure introduction pipe is used, there are problems with durability and reliability. Furthermore, since these parts were exposed to the sides of the carburetor and intake manifold, they were unavoidable, making it difficult to repair the engine.

[Purpose of the invention]

An object of the present invention is to provide an engine idling speed control device that has a small number of parts, has little impact on costs, is compact, does not interfere with engine repair, and has excellent performance. purpose.

[Structure of the invention]

The present invention provides a throttle valve that is eccentrically supported in a closing direction by negative intake pressure of an intake manifold, a valve lever that is integrally attached to a valve shaft of the throttle valve, and a valve lever that is engaged with the valve lever. The accelerator lever is rotatably mounted on the valve shaft and is rotatably operated by the accelerator pedal, and the intake manifold has two pawls for opening and closing the throttle lever. The idling speed control device for an engine is characterized by comprising means for biasing the valve lever in a direction to open the throttle lever.

In carrying out the present invention, the means for biasing the valve lever in the direction of opening the throttle valve may be a torsion spring interposed between the throttle lever and the accelerator lever, or a means for biasing the valve lever in the direction of opening the throttle valve. It can be configured as a heavy joist attached to a valve.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

First, referring to FIGS. 2 to 4 showing a first embodiment of the present invention, reference numeral 1 denotes a carburetor body, and an intake manifold is connected to the downstream side of the carburetor body through a governor (not shown). 2 is a valve shaft mounted eccentrically so that the throttle valve 3 is closed by negative intake pressure; one end of the shaft projects outside of the carburetor body 1, and an accelerator lever 5 and a valve lever are connected to the projecting end. 4 are installed in parallel. That is, the accelerator lever 5 is rotatably fitted on the round shaft portion 2a of the valve shaft 2, and the valve lever 4 is rotatably fitted on the square end portion 2b with respect to the shaft 2, in other words, it rotates integrally with the shaft 2. It is fitted in such a way that it can be rotated, and is fixed in that position by a lock nut 7. In addition, in order to adjust the opening degree of the throttle valve 3 during idling, the adjustment bolt 8 is
It is screwed onto the carburetor body 1 so as to engage with the tip of the valve lever 4. The upper end of the accelerator lever 5 has a claw 5a that engages with the valve lever 4;
5b protrudes at a certain angle. The pawl 5a is for rotating the valve 3 in the closing direction, and the pawl 5b is for rotating the valve 3 in the opening direction. A metal fitting 5c of the same shape is fixed to a fan-shaped portion at the lower end of the accelerator lever 5, and locks an accelerator wire 5d connected to an accelerator pedal (not shown) between the metal fitting 5c and the lever 5. The accelerator lever 5 is subjected to the action of a throttle return spring 5e that acts in a direction to close the throttle valve 3.

Between the valve lever 4 and the accelerator lever 5, there is a pressure applied to the throttle valve 3 by intake negative pressure during idling, which urges the valve lever 4 in the direction of opening the throttle valve 3. A torsion spring 6 is interposed which generates an opening moment that is weaker than the moment in the closing direction. Also,
A full-open stopper 9 that engages with a valve lever 4 is attached to the carburetor body 1 at a position where the throttle valve 3 is fully opened when the accelerator pedal is fully depressed.

Next, the action will be explained.

When an engine for an industrial vehicle such as a forklift is idling as shown in FIG. 4a, the accelerator pedal is not depressed, so the accelerator lever 5 is attracted to the throttle return spring 5e and is in the inoperative position, causing the valve to close. The lever 4 is engaged with the bolt 8 because the throttle valve 3 is closed to the opening degree θ when the intake negative pressure overcomes the spring 6.

If a load is accidentally applied to the power steering or the cargo handling pump in this state, the engine speed will drop, and the intake negative pressure in the intake manifold will also drop (become smaller).
Therefore, the moment that tends to close the throttle valve 3 becomes smaller. Then, since the torsion spring 6 applies a force to the valve lever 4 in the direction of opening the throttle valve 3, the throttle valve 3 receives the closing moment caused by the intake negative pressure that tries to close the valve 3, and the opening by the torsion spring 6. Open until the moments are balanced. The case where the valve lever 4 is opened wide is when the valve lever 4 collides with one pawl 5a of the accelerator lever 5 (No. 4b).
(see figure). The spacing between the valve lever 4 and the pawl 5a of the accelerator lever 5 in Fig. 4a is necessary to obtain the opening degree θ' of the throttle valve 3 that will prevent engine stalling even when the maximum load is applied. be. Therefore, even if the engine does not press the accelerator pedal, the throttle valve 3 opens to increase the flow rate of the air-fuel mixture, maintain the engine speed at or close to the state before the load was applied, and increase the engine output. is the valve opening θ
By opening from the idling state to the maximum θ', the engine can substantially rise and prevent the engine from stalling.

When the load on the engine is removed from this state, the engine speed increases and the intake negative pressure in the intake manifold increases, and accordingly, the closing moment for the throttle valve 3 overcomes the opening moment due to the torsion spring 6. Close the throttle valve 3 until the valve lever 4 integrated therewith engages the adjustment screw 8,
Return to original idling speed.

Also, during normal engine operation, when the accelerator lever 5 is rotated by depressing the accelerator pedal and pulling the accelerator wire 5d, the pawl 5b pushes the valve lever 4 and rotates in unison to the desired opening, resulting in maximum output. In this case, the valve lever 4 engages with the stopper 9 and the throttle valve 3 reaches its maximum opening θ'' (FIG. 4c).

Referring to FIG. 5, which shows a second embodiment of the present invention, this embodiment is different from the valve lever 4 in the first embodiment.
This embodiment has the same structure as the first embodiment, except that a heavy peg 6' is attached to the throttle valve 3 instead of the torsion spring 6 that biases the throttle valve 3 in the direction of opening. Heavy valve 6' is throttle valve 3
It is attached to the position where it is biased to open, that is, at the lower end of the valve 3, and always applies an opening moment to the valve 3. Its weight generates an opening moment that is smaller than the closing moment due to negative intake pressure in the intake manifold when the engine is idling with no load applied, and when the engine is accidentally loaded without depressing the accelerator pedal. This generates an opening moment that is larger than the closing moment when the intake negative pressure decreases as the engine speed decreases.
This heavy stud 6' acts in the same manner as the torsion spring of the first embodiment, and can prevent engine stall.

〔Effect of the invention〕

The present invention relates to an engine idling speed control device for an industrial vehicle such as a forklift, in which the throttle valve is moved between an accelerator lever and a valve lever so that the valve lever faces the intake negative pressure in the intake manifold. By providing a means to apply force in the opening direction, if a load is accidentally applied to the engine during idling,
The throttle valve is opened according to the magnitude of the load, and the engine stall can be effectively and reliably prevented by using a device such as a vacuum diaphragm that has fewer parts than conventional ones, and is inexpensive. Moreover, a highly reliable rotation speed control device can be provided.

Furthermore, there is no need to raise the idling speed to prevent the engine from stalling if the load on the power steering, etc. becomes too high by mistake during idling, so it is recommended to set the idling speed to a low value. This has the effect of reducing fuel consumption and driving noise during idling.

[Brief explanation of drawings]

Fig. 1 shows a conventional engine idling speed control device, Figs. 2 to 4 show a first embodiment of the present invention, Fig. 2 is a longitudinal sectional view, Fig. 3 is an exploded perspective view, and Fig. 4 ac is a diagram showing the operating state, and FIG. 5 is an exploded perspective view showing the second embodiment. 1...Carburetor body, 2...Valve shaft, 2a...Round shaft part, 2b...Square end part, 3...
Throttle valve, 4... Valve lever, 5...
Accelerator lever, 5a, 5b... pawl, 5c... metal fitting, 5d... accelerator wire, 5e... throttle return spring, 6... torsion spring, 6'
... Heavy bolt, 7 ... Lock nut, 8 ... Adjustment bolt, 9 ... Fully open stopper, 10 ... Vacuum, 11 ... Piston rod, 12 ... Pipe, 13 ... Connector, 14 ... Intake manifold, 15 ……spring.

Claims (1)

[Scope of Claims] 1. A throttle valve eccentrically supported in a closing direction by negative intake pressure of an intake manifold, a valve lever integrally attached to the valve shaft of the throttle valve, and the valve lever. an accelerator lever that is rotatably mounted on the valve shaft and is rotatably operated by an accelerator pedal; An idling speed control device for an engine, comprising means for biasing the valve lever in a direction to open the throttle valve against negative pressure. 2. Claim 1, wherein the means for biasing the valve lever in the direction of opening the throttle valve is a torsion spring interposed between the throttle lever and the accelerator pedal.
The idling speed control device for the engine as described in . 3. The engine idling speed control according to claim 1, wherein the means for biasing the valve lever in the direction of opening the throttle valve is a heavy rod attached to the throttle valve. Device.